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Video: Bloomberg quits GOP; is '08 run next?

NEW YORK — New York Mayor Michael Bloomberg left the Republican Party on Tuesday and switched to unaffiliated, a move certain to be seen as a prelude to an independent presidential bid that would upend the 2008 race.

The billionaire former CEO, who was a lifelong Democrat before he switched to the Republican Party in 2001 for his first mayoral run, said the change in his voter registration does not mean he is running for president.

"Although my plans for the future haven't changed, I believe this brings my affiliation into alignment with how I have led and will continue to lead our city," Bloomberg said.

With an estimated worth of more than $5 billion, he easily could finance an independent presidential bid.

The 65-year-old mayor has increasingly been the subject of speculation that he will run as an independent in 2008, despite his repeated promises to leave politics after the end of his term in 2009. He has fueled the buzz with increasing out-of-state travel, a greater focus on national issues and repeated criticism of the partisan politics that dominate Washington.

"The politics of partisanship and the resulting inaction and excuses have paralyzed decision-making, primarily at the federal level, and the big issues of the day are not being addressed, leaving our future in jeopardy," he said in a speech Monday at the start of a University of Southern California conference about the advantages of nonpartisan governing.

Throughout his 5 1/2 years as mayor, Bloomberg has often been at odds with his party and President Bush. He supports gay marriage, abortion rights, gun control and stem cell research, and raised property taxes to help solve a fiscal crisis after the Sept. 11 terrorist attacks.

Video: Matthews analysis
But he never seemed willing to part with the GOP completely, raising money for the 2004 presidential convention and contributing to Bush and other Republican candidates.

Just last year, he told a group of Manhattan Republicans about his run for mayor: "I couldn't be prouder to run on the Republican ticket and be a Republican."